+/// Writes out a C-callable concrete Option<A> struct and utility methods
+pub fn write_option_block<W: std::io::Write>(w: &mut W, mangled_container: &str, inner_type: &str, clonable: bool) {
+ writeln!(w, "#[repr(C)]").unwrap();
+ if clonable {
+ writeln!(w, "#[derive(Clone)]").unwrap();
+ }
+ writeln!(w, "/// An enum which can either contain a {} or not", inner_type).unwrap();
+ writeln!(w, "pub enum {} {{", mangled_container).unwrap();
+ writeln!(w, "\t/// When we're in this state, this {} contains a {}", mangled_container, inner_type).unwrap();
+ writeln!(w, "\tSome({}),", inner_type).unwrap();
+ writeln!(w, "\t/// When we're in this state, this {} contains nothing", mangled_container).unwrap();
+ writeln!(w, "\tNone").unwrap();
+ writeln!(w, "}}").unwrap();
+
+ writeln!(w, "impl {} {{", mangled_container).unwrap();
+ writeln!(w, "\t#[allow(unused)] pub(crate) fn is_some(&self) -> bool {{").unwrap();
+ writeln!(w, "\t\tif let Self::Some(_) = self {{ true }} else {{ false }}").unwrap();
+ writeln!(w, "\t}}").unwrap();
+ writeln!(w, "\t#[allow(unused)] pub(crate) fn take(mut self) -> {} {{", inner_type).unwrap();
+ writeln!(w, "\t\tif let Self::Some(v) = self {{ v }} else {{ unreachable!() }}").unwrap();
+ writeln!(w, "\t}}").unwrap();
+ writeln!(w, "}}").unwrap();
+
+ writeln!(w, "#[no_mangle]").unwrap();
+ writeln!(w, "/// Constructs a new {} containing a {}", mangled_container, inner_type).unwrap();
+ writeln!(w, "pub extern \"C\" fn {}_some(o: {}) -> {} {{", mangled_container, inner_type, mangled_container).unwrap();
+ writeln!(w, "\t{}::Some(o)", mangled_container).unwrap();
+ writeln!(w, "}}").unwrap();
+
+ writeln!(w, "#[no_mangle]").unwrap();
+ writeln!(w, "/// Constructs a new {} containing nothing", mangled_container).unwrap();
+ writeln!(w, "pub extern \"C\" fn {}_none() -> {} {{", mangled_container, mangled_container).unwrap();
+ writeln!(w, "\t{}::None", mangled_container).unwrap();
+ writeln!(w, "}}").unwrap();
+
+ writeln!(w, "#[no_mangle]").unwrap();
+ writeln!(w, "/// Frees any resources associated with the {}, if we are in the Some state", inner_type).unwrap();
+ writeln!(w, "pub extern \"C\" fn {}_free(_res: {}) {{ }}", mangled_container, mangled_container).unwrap();
+ if clonable {
+ writeln!(w, "#[no_mangle]").unwrap();
+ writeln!(w, "/// Creates a new {} which has the same data as `orig`", mangled_container).unwrap();
+ writeln!(w, "/// but with all dynamically-allocated buffers duplicated in new buffers.").unwrap();
+ writeln!(w, "pub extern \"C\" fn {}_clone(orig: &{}) -> {} {{ orig.clone() }}", mangled_container, mangled_container, mangled_container).unwrap();
+ }
+}
+